Water dispersible films are useful in many applications. In the household and industrial markets, the use of water dispersible films in unit dose delivery systems provide several benefits for consumers including ease and convenience of use, low cost, and increased safety for the user due to a reduction in exposure to chemicals present in cleaning formulations. Much of the art of packaging unit dose detergents relates to the development of the water dispersible film package. Presently, water dispersible packaging films based on vinyl alcohol-vinyl acetate copolymers, or more commonly known as partially hydrolyzed polyvinyl alcohol homopolymers (PVOH) and its copolymers with alkyl cellulose compounds and carboxylic acids have remained the predominant film technology due to their rapid water dispersibility.
Liquid laundry detergent compositions are usually formulated with high water content of about 70 to 90 weight percent of water. The use higher water content possesses several advantages, including faster delivery and dispersibility of the formulation ingredients. Currently, however, the water dispersible unit dose pouch or packets fabricated for packaging unit dose liquid laundry detergents are unsuitable for packaging liquid laundry detergents with high water content. In fact current unit dose liquid laundry detergents packaged in PVOH-based water dispersible pouch or packets are highly concentrated heavy-duty liquid formulations with low levels of water contents in an amount of about 10 to 24 weight percent of water. In these formulations, the use of low water content is strictly limited to about 10 weight percent of water to ensure compatibility of the liquid detergent with the water dispersible pouch and prevent premature dissolution and breakdown of the pouch. Due to the low water content, liquid unit dose systems require higher amounts of organic solvent system compared to their liquid laundry detergents counterparts. The use of higher amounts of organic co-solvent such as propylene glycol, ethylene glycol, or glycerine and their combinations allows improved processing and compatibility of the liquid detergent and the packaging film. These solvents unfortunately add cost to the detergent formulation without providing any additional cleaning benefit.
Another key ingredient in liquid detergent formulations is organic neutralizers, such as alkalis. Alkalis are most commonly used in laundry detergents to provide the appropriate pH and high alkalinity. The most effective alkalis in laundry detergents are sodium and potassium salts of silicates, carbonates, and hydroxides. These are typically preferred due to their effectiveness in providing improved soil and dirt removal, and preventing redeposition. In the current unit dose liquid detergents however, the use of organic alkalis are especially problematic due to the incompatibility with the PVOH-based packaging film. Consequently, organic amines such as monoethanol amine are typically used as the neutralizer of choice, further adding cost to the unit dose detergent system.
There is therefore a need for film compositions useful for the fabrication of unit dose articles for packaging liquid formulations with high water content from about 10 to about 95 weight percent of water.